Republican John McCain has quickly closed the gap between himself and Democratic rival Sen. Barack Obama in several key battleground states even as the Arizona senator struggles to break through the wall-to-wall coverage of Obama's trip to Europe and the Middle East this week.

McCain and Obama are in a statistical dead heat in Colorado, Michigan and Minnesota while the Illinois senator has a more comfortable double-digit edge in Wisconsin, according to polling conducted by Quinnipiac University for washingtonpost.com and the Wall Street Journal during the past week. Only in Colorado, however, does McCain hold a greater percentage of the vote share than Obama.

The economy is still the dominant concern of voters in each state. Nearly six in ten respondents in Michigan, a state crippled by the dire problems of the auto industry, cited the economy as the single most important issue in their decision this fall. The war in Iraq ranked second in terms of voter priorities but was named by less than one in five respondents in each state. Potential hot button issues such as terrorism and illegal immigration were cited by fewer than 10 percent of voters in ranking their top priorities.

The surveys are part of a four-month long effort to measure voter sentiment in key battleground states that could determine the outcome of the race. The path to the presidency runs through a handful of battleground states, as both Obama and McCain seek the 270 electoral votes needed to win the White House. Thus, the four states surveyed in this project provide a snapshot of where things stand less than four months before Election Day.

The first in the series of polls, conducted in the four states in mid-June, showed Obama comfortably ahead of McCain in Wisconsin and Minnesota while the races in Michigan and Colorado were closer although Obama still held the lead. The latest polling, showing a much tighter race, was conducted July 14 to 22, during Obama's high-profile trip to the Middle East.

National polling suggests Obama retains a steady but statistically significant edge. In the most recent Washington Post/ABC News survey, Obama held a 50 percent to 42 margin over McCain; in the latest NBC/Wall Street Journal poll, released last night, Obama leads 47 percent to 41.

While both campaigns are heavily engaged on television in most of these states, it's not immediately clear from the data what accounted for McCain's rapid rise -- particularly in Minnesota and Colorado.

One possible reason is the campaign's focus over the last month on the war in Iraq and national security concerns more broadly. McCain's campaign has hammered home the idea that Obama was mistaken in his opposition to the surge of U.S. troops last year and is wrong now about his proposed 16-month timetable for withdrawing troops.

Voters in all four states seem to agree. Asked whether they would prefer a "fixed date" for withdrawal or to "keep troops in Iraq until the situation is more stable," majorities in all four states preferred the latter option despite the fact that similar majorities in each state say that America was wrong to go to war in Iraq.

Those results suggest that while Obama's initial opposition to the war plays well with voters, his plan to remove troops from the country within 16 months of taking office as president is less well received. Obama's plan did, however, receive a major boost earlier this week when Iraqi Prime Minister Nouri al-Maliki said his government would like U.S Forces to be out of the country by 2010.

Other internal numbers in the battleground polls are less rosy for McCain. Nearly one-quarter of voters in each of the four states said McCain's age -- he will be 72 at the time of the election -- makes them less likely to vote for him. Numbers like that may put more pressure on McCain to pick someone considerably younger than him -- Gov. Tim Pawlenty (Minn.) or Sen. John Thune (S.D.) -- as his vice presidential running mate.

The national political environment -- as reflected in these four statewide polls -- also seems to suggest major hurdles for McCain in the fall. President George W. Bush remains a decidedly unpopular figure to the general public with no more than 31 percent in any of the four states approving of the job he is doing. The numbers are even more daunting among self-identified independents who typically make up the swing vote in a presidential election. In Colorado, where independents have traditionally leaned toward Republicans, seven in ten unaffiliated voters expressed disapproval with the job Bush is doing. Those numbers are nearly identical in each of the other three states.

The polls also reveal widespread pessimism about the future of the country -- never a good sign for the candidate running under the party banner of the incumbent. In Minnesota, just one in five voters called themselves very or somewhat satisfied with "the way things are going in the nation today" while a whopping 77 percent pronounced themselves dissatisfied. The outlook was even worse in the other three states, with dissatisfied voters at 78 percent in Colorado, 81 percent in Wisconsin, and 84 percent in Michigan.

However, independents generally were far more evenly divided between Obama and McCain than in last month's Quinnipiac/washingtonpost.com/Wall Street Journal surveys.

A month ago, Obama led McCain among Independents by anywhere from 21 points (Minnesota) to eight points (Michigan). In the most recent set of data, McCain actually outperforms Obama by three points among independents in Michigan while losing that crucial voting bloc far more narrowly in Colorado (Obama +8), Minnesota (Obama +8) and Wisconsin (Obama +9).

Two of the states in the battleground surveys -- Minnesota and Colorado -- are also playing host to high profile Senate races. In each, the news is good for Republicans.

In Minnesota, Sen. Norm Coleman has built a 53 percent to 38 percent edge over entertainer Al Franken ¿ thanks in no small part to a series of gaffes by the former "Saturday Night Live" star. In Colorado, former Rep. Bob Schaffer (R) has pulled into a dead heat with Rep. Mark Udall (D), an affirmation of Republicans' insistence that the contest will be among the closest in the country.